When Rio de Janeiro bid to host the 2016 Olympics, it cited as a trump card the experience and infrastructure the city had gathered in hosting the 2007 Pan American Games. Opponents, however, pointed to Rio’s broken promises from the 2007 event, like the metro lines and highways the city vowed to build but never did. Nevertheless, the International Olympic Committee (IOC) overlooked those protests and decided the self-described “Marvelous City” would become the first South American venue to hold the world’s biggest sporting event.

Now, almost four years after that momentous decision, it looks increasingly like Rio’s Pan Am experience was wanting. The Pan Am Games’ João Havelange Stadium — now intended for the track-and-field competitions in the 2016 Olympics — has just been closed because it’s in danger of collapse. The velodrome is about to be knocked down because it isn’t up to Olympic standards. And a handful of other venues are being modernized or upgraded because they simply aren’t good enough.

“They said that one of the reasons the Pan American games were so overbudget was because the installations were built to an Olympic standard, and we can see now that is clearly not the case,” says Alberto Murray, a former member of the Brazilian Olympic Committee and a critic of Rio’s preparations. “What we are seeing is not new. It is something that has been getting worse over time.”

The closure of the track-and-field stadium comes at a sensitive moment for Rio, the former capital whose decades-long decline was arrested only recently thanks to the election of a progressive mayor and a flood of pre-Olympic (and oil and gas) investment. Over the weekend, a 21-year-old American woman was gang-raped on a bus — a grim reminder that violence is never far from the surface in Brazil. Now, a scandal over shoddy workmanship on the stadium raises fresh questions over the city’s suitability as Olympic host.

The João Havelange arena is currently the city’s main soccer stadium. Some of the huge metal beams holding up the roof have shifted out of position and rusted through, according to engineers. They warned that the roof could topple if wind speeds top 63 km/h. Rio’s Mayor Eduardo Paes immediately closed the site, known as the Engenhão after the neighborhood where it is located, and could not say when it might reopen. “The Engenhão is going to stay closed for as long as it takes and will only open when there is a definitive solution,” Paes says. “Our priority is making sure people are safe.”

Although he says it would not alter plans to host Olympic events there, there must now be some doubt about whether the arena is a suitable venue. The problems are not restricted to the structure. Faulty electrical installations caused floodlights to fail in one soccer match, players routinely complain about the barren and uneven grass, and corroded pipes have left executive boxes and bathrooms without water. “A stadium that was budgeted to cost 80 million reals [around $40 million] and ended up costing 360 million reals [around $180 million] just five or so years later, and then shows this kind of problem,” says Maurício Assumpçao, president of Botafogo, one of the soccer teams that plays there. “Obviously this has to be investigated with great care.”

The problem for Rio — and the IOC — is not just the quality of the construction. A bigger worry, certainly for Rio’s taxpayers, is poor planning. The Pan Am games were supposed to provide the organizational basis for the Olympics, with proponents claiming that only 28 % of the venues used in 2016 need to be constructed from scratch. But several of the venues built or renovated for the 2007 event must now undergo costly upgrades or be demolished and rebuilt. The aquatic park is too small and new venues must be built for swimming and diving; the gymnasium for volleyball will have to be modernized; and the velodrome is being moved lock, stock and barrel to another state because it doesn’t meet Olympic specifications.

The Maracanã, the legendary soccer stadium that will host the 2014 World Cup final and the opening and closing ceremonies of the 2016 Olympics, is currently undergoing its third renovation in little more than a decade. The cost so far exceeds $500 million and much of the work undoes previous reconstruction. The same people who oversaw the Pan American games are running Olympic planning. They have not commented on the latest developments.